FIG. 1 shows a conventional OLED device 100. The OLED device comprises one or more organic functional layers 110 between first and second electrodes 105 and 115 formed on a substrate 101. The electrodes can be patterned to form, for example, a plurality of OLED cells to create a pixelated OLED device. Bond pads 150, which are coupled to the first and second electrodes, are provided to enable electrical connections to the OLED cells. A cap 160 is formed over the substrate to encapsulate the device, protecting the OLED cells from the environment such as moisture and/or air.
The substrate is preferably made from glass due to its good barrier properties against moisture or air. Glass substrates provide other advantages including a smooth surface, temperature and dimensional stability as well as availability of raw materials and processes.
For flexible applications, such as chip cards, the overall device thickness of the devices need to be less than about 0.6 mm. As such, conventional OLEDs are incompatible since they are too thick and are typically more than 2 mm thick. To reduce the overall thickness and impart mechanical flexibility, thin or ultra thin glass substrates having a thickness of less than 0.4 mm are used. However, the thin glass substrates are fragile and susceptible to breakage due to mechanical stress, such as bending of the chip card.
As evidenced from the above discussion, it is desirable to provide a thin flexible device formed of a thin glass substrate that is not susceptible to breakage.